Pen



FIG. 1 is a perspective view of a pen showing my new design;

FIG. 2 is the front elevational view of the pen;

FIG. 3 is the right side elevational view of the pen; the left side being a mirror image thereof;

FIG. 4 is the rear elevational view of the pen;

FIG. 5 is the top plan view; and,

FIG. 6 is the bottom plan view. 

The ornamental design for a pen, as shown and described. 